The present invention relates to a restraint system for an occupant of a motor vehicle with support elements that can be transferred from a storage position to a restraint position, and flexible casing elements that are disposed between the support elements and have air flow openings, such that the support elements with the flexible casing elements enclose a restraint volume in the restraint position.
Such restraint systems are for example known from the series-production of passenger motor vehicles in the form of airbags in multiple embodiments. These airbags generally comprise a retaining volume limited by a covering, which can be enlarged from a storage position into a restraint position. The airbag which is usually folded in the storage position is thereby filled with gas in a pyrotechnical manner when an accident is detected, so that it deploys suddenly towards the occupant who dislocates forward, and thus contributes at least indirectly to his restraint. Accordingly, the gas introduced into the covering, usually by means of a gas generator, serves for the deployment of the airbag on the one hand and for achieving the restraint of the respective person on the other hand.
German patent document DE 41 34 837 C2 discloses an airbag for the protection of a vehicle occupant, which has an air-impermeable cloth on the side facing the occupant and an air-permeable cloth on the side of the vehicle body. A disk-shaped part which is movable freely at the edge is arranged at the air-permeable cloth. When the airbag is inflated, additional air passes through the air-permeable cloth and rotates the free part upwards. The open region of the air-permeable cloth is thereby increased. If the airbag collides with the occupant after its expansion, the free part partially covers the air breathing part formed by the air-permeable cloth. The open region of the air breathing part is thereby reduced, so that the air passage from the interior to the exterior of the airbag is also reduced correspondingly.
Furthermore, a support structure airbag is known from the specification P 811338 (internal reference) published later. The support structure can be displaced from a storage position to a restraint position by inflating a plurality of hollow bodies connected to each other, forming a channel system by means of a gas in a targeted manner. Surface elements with air flow openings are provided between the hollow bodies. The surface elements form an airbag together, which encloses the restraint volume. During the deployment of the airbag, air flows through the air flow openings into the interior of the airbag, and when restraining the vehicle occupant, the air flows again to the exterior through the air flow openings. The outflow of the air takes place with the same speed as the inflow apart from air flow openings, which are covered by the occupant himself during an impact. In this case it is however necessary that the restraining function is sustained for a longer period.
It is thus one object of the present invention to sustain the restraining function of a so-called “support structure airbag” for a longer period of time and in a more targeted manner.
This and other objects and advantages are achieved by the restraint system according to the invention for an occupant of a motor vehicle with support elements, which can be transferred from a storage position to a restraint position, and flexible casing elements, which are arranged between the support elements and have air flow openings, such that the support elements with the flexible casing elements enclose a restraining volume with the flexible casing elements in the restraint position. A resistance element is arranged at each of the air flow openings so as to impede or prevent an outflow of air from the restraint volume compared to the inflow at the respective air flow opening.
It is achieved by the resistance elements in an advantageous manner that the air can flow into the airbag formed by the casing elements faster than it can flow out. The desired short deployment time can thereby be combined with the required restraining effect.
The flexible casing elements can form an outer layer as a covering corresponding to one embodiment, and a flexible planar material which embodies several resistance elements can be arranged within the covering as an inner layer, wherein the inner layer also has air flow openings, which are however offset in their lateral position with regard to the air flow openings of the outer layer. In this manner, a check valve function can be realized in a very simple manner by two fabrics or foil layers.
Furthermore, one layer of flexible casing elements can have a supporting function and another layer or a material different from the layer can have a sealing function. The supporting layer can especially be on the outside and the sealing layer or the sealing material can be on the inside during the deployment of the flexible casing elements.
The inner layer can especially be more flexible than the outer layer. Thereby, the outer layer has a support function, and the inner layer has a sealing function.
The inner and/or the outer layer can further have a fabric, and the air flow openings can be formed by displacing weft threads or warp threads. It is thereby prevented that the fabric is damaged when forming the air flow opening and that the airbag loses stability thereby. The inner and/or the outer layer can alternatively have a similar fabric, and the air flow openings can be formed by displacing from one or several elements of the respective layer or the layers.
The resistance elements are preferably respectively individual planar materials in their function as check valves, which are mounted to the casing elements with the air flow openings. The term “planar material” is generally meant to be foils, cloths, and other fabrics. They can be moved easily through air flows, so as to take on a check valve function.
The resistance elements can especially be mounted in a U-shaped manner over the respective air flow opening. The U-shaped resistance elements then bend with an increased inner pressure and close the air flow openings.
In a further embodiment, the resistance elements can respectively be fastened around the respective air flow opening at least three points. During the inflow, an approximately dome-shaped form of the resistance elements results, and during the outflow of the air, they bend again and press against the air flow opening.
It is provided corresponding to another further development that each resistance element is held in a position in which the respective air flow opening is closed at least partially. In this manner, a high restraining force is already available shortly after the complete deployment of the airbag.
The resistance elements can further be fringes or fiber pieces of the casing elements. They are thereby part of the casing elements, and a second layer can be foregone.
The resistance elements can further consist of free particles, adhesive or melted fabric parts, which are brought or melted into the air flow openings in the restraint position of the restraint system. The release of the particles, the application of the adhesive, or the melting on of the openings takes place towards the end of the airbag deployment.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.